Systems and methods for multi-AP transmissions with uniform coverage

Abstract

Systems and methods for multi-AP transmissions with uniform coverage are disclosed. A method for multiple access point (AP) transmissions includes receiving a plurality of duplicate beacons, one duplicate beacon from each of a plurality of APs, each of the plurality of duplicate beacons including a common information portion and an AP-specific information portion; decoding at least one of the plurality of common information portions to obtain a first parameter; decoding the plurality of AP-specific information portions to obtain a plurality of second parameters, each second parameter associated with one of the plurality of APs; generating feedback based on the first parameter and the plurality of second parameters and a number of the plurality of APs; and transmitting the feedback to at least one of the plurality of APs.

Description

[0001] This application is a divisional application of the Chinese invention patent application with application date of March 6, 2020 and application number 202080027003.8.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of U.S. Provisional Application No. 62 / 815,753, filed on March 8, 2019, the contents of which are incorporated herein by reference. Summary of the invention

[0004] The present invention discloses a method for multi-access point (AP) transmission. The method includes: receiving a repeated beacon from each of a plurality of APs, each received repeated beacon including a common information part and an AP-specific information part; decoding at least a subset of the received common information part to obtain a first parameter; decoding the received AP-specific information part to obtain a second parameter of each of the plurality of APs; performing calculation based on the first parameter, the obtained second parameter and the number of the plurality of APs to obtain a calculation result; and transmitting feedback based on the calculation result to the plurality of APs.

[0005] The present invention discloses a wireless transmit / receive unit (WTRU) for multi-access point (AP) transmission. The WTRU includes: a transceiver configured to receive repeated beacons from each of a plurality of APs, each received repeated beacon including a common information part and an AP-specific information part; and a processor configured to decode at least a subset of the received common information part to obtain a first parameter; decode the received AP-specific information part to obtain a second parameter of each of the plurality of APs; and perform calculation based on the first parameter, the obtained second parameter and the number of the plurality of APs to obtain a calculation result, wherein the transceiver is further configured to transmit feedback based on the calculation result to the plurality of APs.

[0006] The present invention discloses a method for multi-access point (AP) transmission, the method comprising: receiving multiple repeated beacons, one repeated beacon from each of multiple APs, each of the multiple repeated beacons comprising a common information part and an AP-specific information part; decoding at least one of the multiple common information parts to obtain a first parameter; decoding the multiple AP-specific information parts to obtain a plurality of second parameters, each second parameter being associated with one of the multiple APs; generating feedback based on the first parameter and the multiple second parameters and the number of the multiple APs; and transmitting the feedback to at least one of the multiple APs. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] A more detailed understanding may be obtained from the following description given by way of example in conjunction with the accompanying drawings, in which like reference numerals indicate like elements, and in which:

[0008] Figure 1A is a system diagram illustrating an exemplary communication system in which one or more disclosed embodiments may be implemented;

[0009] Figure 1B It is shown that according to one embodiment, Figure 1A A system diagram of an exemplary wireless transmit / receive unit (WTRU) for use within the communication system shown;

[0010] Figure 1C It is shown that according to one embodiment, Figure 1A A system diagram of an exemplary radio access network (RAN) and an exemplary core network (CN) used within the illustrated communication system;

[0011] Figure 1D It is shown that according to one embodiment, Figure 1A A system diagram of another exemplary RAN and another exemplary CN used in the communication system shown;

[0012] Figure 2 An example of cooperative OFDMA fractional frequency reuse (FFR) is shown;

[0013] Figure 3 An exemplary resource allocation associated with cooperative OFDMA FFR is shown;

[0014] Figure 4 An exemplary cooperative nulling / cooperative beamforming (CN / CB) scenario is shown;

[0015] Figure 5 An exemplary SU joint precoding multi-AP transmission or collaborative SU beamforming scenario is shown;

[0016] Figure 6 An exemplary MU joint precoding multi-AP transmission or collaborative MU beamforming scenario is shown;

[0017] Figure 7 An exemplary scenario of beacon transmission coverage of cell edge STAs is shown;

[0018] Figure 8 shows an architecture in which a STA can be associated with an AP in a traditional manner or via a virtual AP;

[0019] Fig. 9 An architecture is shown in which a STA is associated only with a virtual AP;

[0020] Fig.10 shows multiple AP repeated beacons transmitted sequentially in different time slots;

[0021] Fig.11 shows multiple AP repeating beacons transmitted concurrently;

[0022] Fig.12 An example is shown in which a lead AP may initiate multiple AP repeated beacon transmissions;

[0023] Fig.13 An example is shown in which a lead AP may transmit a multi-AP beacon trigger frame;

[0024] Fig.14 An exemplary sequential transmission scheme with multiple channels is shown;

[0025] Fig.15 An example of a flexible repeating beacon transmission with a repeating beacon transmission interval is shown;

[0026] Fig.16 An exemplary TBTT / beacon window and t_i are shown;

[0027] Fig.17 An exemplary reserve / fill signal is shown;

[0028] Fig.18 Exemplary repeated beacon measurements and feedback are shown;

[0029] Fig.19 An exemplary flow chart of a method according to an embodiment of the present application is shown;

[0030] Fig. 20 An exemplary aggregate beacon structure is shown;

[0031] Fig.21 An exemplary split beacon structure is shown;

[0032] Fig. 22 An exemplary allowable transmission window for preventing AP-specific beacon overlap is shown;

[0033] Fig.23 An exemplary disallowed transmission window for preventing AP-specific beacon overlap is shown; and

[0034] Fig.24 Exemplary single / multi-AP feedback polling / triggering is shown. DETAILED DESCRIPTION

[0035] Figure 1A1 is a schematic diagram illustrating an exemplary communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, messaging, broadcast, etc. to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content through sharing of system resources (including wireless bandwidth). For example, the communication system 100 may employ one or more channel access methods such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), zero tail unique word discrete Fourier transform spread OFDM (ZT-UW-DFT-S-OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multi-carrier (FBMC), etc.

[0036] like Figure 1A As shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104, a core network (CN) 106, a public switched telephone network (PSTN) 108, the Internet 110 and other networks 112, but it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d (any of which may be referred to as a station (STA)) may be configured to transmit and / or receive wireless signals and may include user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smart phone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial and / or automated process chain environment), a consumer electronic device, a device operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0037] The communication system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device that is configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a NodeB, an evolved NodeB (eNB), a Home NodeB, a Home evolved NodeB, a next generation NodeB such as a gNodeB (gNB), a new radio (NR) NodeB, a site controller, an access point (AP), a wireless router, and the like. Although the base stations 114a, 114b are each depicted as a single element, it should be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0038] The base station 114a may be part of the RAN 104, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), a relay node, etc. The base station 114a and / or the base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in a licensed spectrum, an unlicensed spectrum, or a combination of licensed and unlicensed spectrums. A cell may provide coverage of wireless services to a specific geographic area, which may be relatively fixed or may change over time. The cell may be further divided into cell sectors. For example, a cell associated with the base station 114a may be divided into three sectors. Therefore, in one embodiment, the base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In one embodiment, the base station 114a may employ multiple-input multiple-output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and / or receive signals in a desired spatial direction.

[0039] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0040] More specifically, as noted above, the communication system 100 may be a multiple access system and may employ one or more channel access schemes such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base station 114a in the RAN 104 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may use Wideband CDMA (WCDMA) to establish the air interface 116. WCDMA may include communication protocols such as High Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High Speed ​​Uplink (UL) Packet Access (HSUPA).

[0041] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and / or Advanced LTE (LTE-A) and / or Advanced LTE Pro (LTE-A Pro).

[0042] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR radio access, which may establish the air interface 116 using NR.

[0043] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access together, for example using dual connectivity (DC) principles. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., eNBs and gNBs).

[0044] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), GSM Enhanced Data Rates for Evolution (EDGE), GSM EDGE (GERAN), etc.

[0045] Figure 1A The base station 114b in the may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in a local area, such as a business location, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a picocell or a femtocell. As Figure 1A As shown, the base station 114 b may have a direct connection to the Internet 110. Therefore, the base station 114 b may not need to access the Internet 110 via the CN 106.

[0046] The RAN 104 may be in communication with the CN 106, which may be any type of network configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, delay requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not described in detail in the specification, the CN 106 may be configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. Figure 1AAlthough not shown in the figure, it will be appreciated that the RAN 104 and / or the CN 106 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 or a different RAT. For example, in addition to being connected to the RAN 104, which may utilize NR radio technology, the CN 106 may also be in communication with another RAN (not shown) that employs GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0047] The CN 106 may also act as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and / or the Internet Protocol (IP) in the TCP / IP Internet protocol suite. The networks 112 may include wired and / or wireless communication networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 or a different RAT.

[0048] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks via different wireless links). Figure 1A The illustrated WTRU 102c may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0049] Figure 1B is a system diagram illustrating an exemplary WTRU 102. Figure 1B As shown, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138. It will be appreciated that the WTRU 102 may include any subcombination of the foregoing elements while remaining consistent with an embodiment.

[0050] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), any other type of integrated circuit (IC), a state machine, etc. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functions that enable the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. Although Figure 1B The processor 118 and the transceiver 120 are depicted as separate components, but it is understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0051] The transmit / receive element 122 may be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) via an air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In one embodiment, the transmit / receive element 122 may be a transmitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive RF and light signals. It should be appreciated that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0052] Although the transmit / receive element 122 is Figure 1B 1 as a single element, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0053] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and to demodulate signals received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0054] The processor 118 of the WTRU 102 may be coupled to a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit) and may receive user input data therefrom. The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from and store data in any type of suitable memory, such as a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from and store data in a memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0055] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control power to other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel-metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0056] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or in lieu of the information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by any suitable location-determination method while remaining consistent with an embodiment.

[0057] The processor 118 may also be coupled to other peripherals 138, which may include one or more software modules and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, Module, FM radio unit, digital music player, media player, video game player module, Internet browser, virtual reality and / or augmented reality (VR / AR) device, activity tracker, etc. Peripheral device 138 may include one or more sensors. The sensor may be one or more of the following: gyroscope, accelerometer, Hall effect sensor, magnetometer, orientation sensor, proximity sensor, temperature sensor, time sensor; geographic location sensor, altimeter, light sensor, touch sensor, magnetometer, barometer, gesture sensor, biometric sensor, humidity sensor, etc.

[0058] The WTRU 102 may include a full-duplex radio for which transmission and reception of some or all signals (e.g., associated with specific subframes for UL (e.g., for transmission) and DL (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit for reducing and / or substantially eliminating self-interference via hardware (e.g., choke) or via signal processing performed by a processor (e.g., a separate processor (not shown) or via the processor 118). In one embodiment, the WTRU 102 may include a half-duplex radio for which transmission and reception of some or all signals (e.g., associated with specific subframes for UL (e.g., for transmission) or DL ​​(e.g., for reception)) may be concurrent and / or simultaneous.

[0059] Figure 1C 1 is a system diagram illustrating the RAN 104 and the CN 106 according to one embodiment. As described above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0060] The RAN 104 may include evolved Node-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of evolved Node-Bs while remaining consistent with an embodiment. The evolved Node-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the evolved Node-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the evolved Node-B 160a, for example, may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0061] Each of the evolved Node Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, etc. Figure 1C As shown, the eNode-Bs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0062] Figure 1C The illustrated CN 106 may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (PGW) 166. Although the foregoing elements are depicted as part of the CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0063] The MME 162 may be connected to each of the evolved Node-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, etc. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0064] The SGW 164 may be connected to each of the evolved Node-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring the user plane during inter-evolved Node-B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, and the like.

[0065] The SGW 164 may be connected to the PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0066] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include, or may be in communication with, an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers.

[0067] Although the WTRU Figures 1A to 1D Although described as a wireless terminal, it is contemplated that in certain representative embodiments, such a terminal may (eg, temporarily or permanently) use a wired communications interface with a communications network.

[0068] In a representative embodiment, the other network 112 may be a WLAN.

[0069] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for a BSS and one or more stations (STAs) associated with the AP. The AP may have access or an interface to a distribution system (DS) or another type of wired / wireless network that carries traffic to and / or carries traffic away from the BSS. Traffic originating from outside the BSS and leading to the STA may be reached by the AP and may be delivered to the STA. Traffic originating from the STA and leading to a destination outside the BSS may be sent to the AP to be delivered to the corresponding destination. Traffic between STAs within the BSS may be sent by the AP, for example, wherein the source STA may send traffic to the AP, and the AP may deliver traffic to the destination STA. Traffic between STAs within the BSS may be considered and / or referred to as point-to-point traffic. Point-to-point traffic may be sent between the source and destination STAs (e.g., directly between them) using a direct link setup (DLS). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunnel DLS (TDLS). A WLAN using an independent BSS (IBSS) mode may not have an AP, and STAs (eg, all STAs) within or using the IBSS may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad-hoc" communication mode.

[0070] When using the 802.11ac infrastructure operating mode or a similar operating mode, the AP may transmit a beacon on a fixed channel (such as a primary channel). The primary channel may be a fixed width (e.g., a 20 MHz wide bandwidth) or a dynamically set width. The primary channel may be an operating channel of the BSS and may be used by the STA to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access / collision avoidance (CSMA / CA) may be implemented, for example, in an 802.11 system. For CSMA / CA, a STA (e.g., each STA) (including the AP) may sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0071] High throughput (HT) STAs may communicate using a 40 MHz wide channel, for example, via a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0072] Very high throughput (VHT) STA can support 20MHz, 40MHz, 80MHz and / or 160MHz wide channels. 40MHz and / or 80MHz channels can be formed by combining continuous 20MHz channels. A 160MHz channel can be formed by combining 8 continuous 20MHz channels, or by combining two non-continuous 80MHz channels (this can be called 80+80 configuration). For the 80+80 configuration, after channel coding, the data can pass through a segment parser that can divide the data into two streams. Each stream can be processed by inverse fast Fourier transform (IFFT) and time domain processing separately. These streams can be mapped to two 80MHz channels, and data can be transmitted by transmitting STA. At the receiver of the receiving STA, the above-mentioned operation for the 80+80 configuration can be reversed, and the combined data can be sent to the medium access control (MAC).

[0073] 802.11af and 802.11ah support operating modes below 1GHz. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah relative to those used in 802.11n and 802.11ac. 802.11af supports 5MHz, 10MHz, and 20MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz, and 16MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support meter type control / machine type communication (MTC), such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including support for (e.g., only support for) certain bandwidths and / or limited bandwidths. MTC devices may include batteries with battery life above a threshold (e.g., to maintain very long battery life).

[0074] WLAN systems that can support multiple channels and channel bandwidths such as 802.11n, 802.11ac, 802.11af, and 802.11ah include channels that can be designated as primary channels. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a STA (which supports the minimum bandwidth operating mode) from all STAs operating in the BSS. In the example of 802.11ah, for STAs (e.g., MTC-type devices) that support (e.g., only support) 1MHz mode, the primary channel may be 1MHz wide, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAV) settings may depend on the state of the primary channel. If the primary channel is busy, for example, because a STA (supporting only the 1MHz operating mode) is transmitting to the AP, all available frequency bands may be considered busy even if most of the available frequency bands remain idle.

[0075] In the United States, the available frequency band for 802.11ah is 902MHz to 928MHz. In South Korea, the available frequency band is 917.5MHz to 923.5MHz. In Japan, the available frequency band is 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz, depending on the country code.

[0076] Figure 1D 1 is a system diagram illustrating the RAN 104 and the CN 106 according to one embodiment. As noted above, the RAN 104 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0077] The RAN 104 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 104 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, the gNBs 180a, 180b may utilize beamforming to transmit signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a may, for example, use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a. In one embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation techniques. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum, while the remaining component carriers may be on licensed spectrum. In one embodiment, the gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) techniques. For example, the WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0078] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with scalable parameter sets. For example, OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or transmission time intervals (TTIs) of varying or scalable lengths (e.g., containing different numbers of OFDM symbols and / or continuously varying absolute time lengths).

[0079] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c while also not accessing other RANs (e.g., such as the eNodeBs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may use one or more of the gNBs 180a, 180b, 180c as mobility anchor points. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate or connect with the gNBs 180a, 180b, 180c while also communicating or connecting with other RANs, such as the eNode-Bs 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more evolved Node-Bs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the evolved Node-Bs 160a, 160b, 160c may serve as mobility anchors for the WTRUs 102a, 102b, 102c, and the gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0080] Each of the gNBs 180a, 180b, 180c may be associated with a specific cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and / or DL, support of network slicing, interworking between DC, NR, and E-UTRA, routing of user plane data towards a user plane function (UPF) 184a, 184b, routing of control plane information towards an access and mobility management function (AMF) 182a, 182b, etc. Figure 1D As shown, gNBs 180a, 180b, and 180c may communicate with each other via an Xn interface.

[0081] Figure 1DThe illustrated CN 106 may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and possible data networks (DNs) 185a, 185b. Although the aforementioned elements are depicted as part of the CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0082] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c via the N2 interface in the RAN 104 and may serve as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRU 102a, 102b, 102c, support of network slicing (e.g., handling of different protocol data unit (PDU) sessions with different requirements), selecting a specific SMF 183a, 183b, management of registration areas, termination of non-access stratum (NAS) signaling, mobility management, etc. The AMF 182a, 182b may use network slicing to customize CN support for the WTRU 102a, 102b, 102c based on the type of services used by the WTRU 102a, 102b, 102c. For example, different network slices may be established for different use cases, such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced mobile broadband (eMBB) access, services for MTC access, etc. The AMF 182a, 182b may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies, such as WiFi.

[0083] The SMF 183a, 183b may be connected to the AMF 182a, 182b in the CN 106 via the N11 interface. The SMF 183a, 183b may also be connected to the UPF 184a, 184b in the CN 106 via the N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b, and configure traffic routing through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing DL data notifications, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0084] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via the N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering DL packets, providing mobility anchoring, etc.

[0085] The CN 106 may facilitate communications with other networks. For example, the CN 106 may include or may communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to the DNs 185a, 185b via the UPFs 184a, 184b via the N3 interfaces to the UPFs 184a, 184b and the N6 interfaces between the UPFs 184a, 184b and the local DNs 185a, 185b.

[0086] Given that Figures 1A to 1D as well as Figures 1A to 1D Corresponding to the description of the present invention, one or more or all of the functions described herein with reference to one or more of the following may be performed by one or more simulation devices (not shown): WTRU102a-d, base station 114a-b, evolved Node B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF182a-b, UPF 184a-b, SMF 183a-b, DN 185a-b and / or any other device described herein. The simulation device may be one or more devices configured to emulate one or more or all of the functions described herein. For example, the simulation device may be used to test other devices and / or simulate network and / or WTRU functions.

[0087] The simulation device may be designed to implement one or more tests of other devices in a laboratory environment and / or in an operator network environment. For example, the one or more simulation devices may perform one or more or all functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. The one or more simulation devices may perform one or more functions or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The simulation device may be directly coupled to another device for testing purposes and / or perform testing using over-the-air wireless communications.

[0088] The one or more simulation devices may perform one or more (including all) functions without being implemented / deployed as part of a wired and / or wireless communication network. For example, the simulation device may be used in a test scenario in a test lab and / or a non-deployed (e.g., testing) wired and / or wireless communication network to implement testing of one or more components. The one or more simulation devices may be test equipment. Direct RF coupling and / or wireless communication via RF circuits (e.g., which may include one or more antennas) may be used by the simulation device to transmit and / or receive data.

[0089] In a typical 802.11 network, a STA is associated with a single AP and transmits to and from that AP with little or no cooperation with transmissions in neighboring BSSs. STAs may defer overlapping BSS (OBSS) transmissions based on a completely independent CSMA protocol between BSSs. An 802.11ax system may support some level of cooperation between OBSSs by allowing a spatial reuse process for OBSS transmissions based on an adjusted energy detection threshold (using the OBSS Packet Detection (PD) process), or by understanding the amount of interference that the receiving OBSS STA can tolerate (using the Spatial Reuse Parameters (SRP) process). In this application, unless otherwise noted, the terms STA and WTRU may be used interchangeably.

[0090] Some embodiments facilitate more cooperation between OBSSs, for example by allowing transmissions from multiple APs to a single or multiple STAs. This may be distinguished from, among other things, coordinated multi-point (CoMP) transmissions in 3GPP LTE Release 10. For example, cooperation between OBSSs may be implemented using unlicensed bands and may be specific to the 802.11 protocol.

[0091] In CoMP, multiple eNBs may transmit to the same or multiple WTRUs in the same time and frequency resources using joint processing / transmissions with the goal of improving the total throughput of the WTRUs under consideration. Dynamic cell selection may be viewed as a special case of joint processing, where only one of the set of eNBs is actively transmitting data at any time. On the other hand, multiple eNBs may transmit to different WTRUs in the same time and frequency resources (each eNB serving its own WTRU) using collaborative beamforming / scheduling with the goal of reducing the interference experienced by each WTRU. Due to CoMP in LTE, significant improvements in cell average and / or cell edge throughput may be achieved. Multiple transmit antennas may be assumed to be available for each base station. Simultaneous interference suppression (for other WTRUs) and signal quality optimization (for the desired WTRU) may be performed by spatial domain signal processing at each base station.

[0092] In general, some degree of channel state information may be assumed to be available at the base station (e.g., through explicit feedback). In addition, a certain degree of timing and / or frequency synchronization may be assumed so that more complex signal processing for handling inter-carrier interference (or inter-symbol interference) may be avoided. Furthermore, the level of cooperation between eNBs may affect the specific CoMP schemes that are possible.

[0093] Multi-AP transmission schemes in WLAN can be classified into, for example, collaborative OFDMA, collaborative zeroing / collaborative beamforming (CN / CB) and / or collaborative SU / MU transmission. In the case of collaborative SU transmission, multiple APs transmit to STAs in one resource unit (RU). Collaborative SU transmission may include (in order of increasing complexity) one or more of dynamic point selection, collaborative SU beamforming and / or collaborative MU beamforming. In the case of dynamic point selection, transmission may be dynamically selected from one of a set of APs. Note that this may include HARQ. In the case of collaborative SU beamforming, transmissions are from multiple APs simultaneously and the transmissions may be beamformed. In the case of collaborative MU beamforming, multiple APs transmit data to or receive data from multiple STAs on one RU.

[0094] In cooperative OFDMA, each RU group can be used by only one AP to transmit or receive data. Information can be beamformed or have MU-MIMO on each RU. The complexity can be characterized as relatively low to medium. In a simple cooperative OFDMA scheme, the APs can divide the OFDMA RUs among themselves in a cooperative manner, for example, where each AP is limited to a specific RU. More complex schemes may occur where the AP allows STAs that are not affected by interference or will not affect other STAs to utilize the entire bandwidth while limiting access to STAs that may be affected. This may be referred to as fractional frequency reuse (FFR). Figure 2An example of collaborative OFDMAFFR is shown. Figure 3 An exemplary resource allocation associated with cooperative OFDMA FFR is shown.

[0095] In cooperative nulling / cooperative beamforming (CN / CB), each AP may apply precoding to transmit or receive information to or from its desired STA(s) and suppress interference to or from other STAs. Figure 4 An exemplary CN / CB scenario is shown. Figure 4 As shown, AP1 can transmit information to or receive information from its desired STA (i.e., STA1), and AP2 can transmit information to or receive information from its desired STA (i.e., STA2). AP1 can suppress interference to or from STA2, and AP2 can suppress interference to or from STA2. Note that in this case, the data of each STA may only be needed at its associated AP, although in some specific implementations, channel information from another STA may be needed at both APs.

[0096] In cooperative SU or MU (SU / MU) transmission, multiple APs may cooperate to transmit or receive information to or from a single STA or multiple STAs simultaneously. In this case, both the channel information and data of the STAs may be needed at both APs. Cooperative SU / MU transmission may include cooperative SU transmission and / or cooperative MU beamforming.

[0097] In cooperative SU transmission, multiple APs may transmit to a STA in one RU. Cooperative SU transmission may include (in order of increasing complexity): dynamic point selection and / or cooperative SU beamforming or joint precoding. In dynamic point selection, a transmission may be dynamically selected from one of a set of APs. The selection may incorporate HARQ. In cooperative SU beamforming or joint precoding, transmissions may come from multiple APs simultaneously, and the transmissions may be beamformed or precoded to the desired STA on one or more RUs. Figure 5 An exemplary SU joint precoding multi-AP transmission or collaborative SU beamforming scenario is shown. Figure 5 As shown, there are two APs (AP1 and AP2) and only one STA (STA1). AP1 and AP2 may transmit to STA1 simultaneously, and the transmissions may be beamformed or precoded to STA1 on one or more RUs.

[0098] In collaborative MU beamforming, multiple APs can transmit data to or receive data from multiple STAs on one or more RUs. Figure 6An exemplary MU joint precoding multi-AP transmission or collaborative MU beamforming scenario is shown. Figure 6 As shown, there are two APs (AP1 and AP2) and two STAs (STA1 and STA2). Each AP can transmit data to or receive data from the two STAs.

[0099] Some embodiments discussed herein relate to joint multi-AP transmission scenarios. The following description will describe some problems and technical solutions for solving the problems according to the present application. The following description will first describe the technical problems to be solved by the present application.

[0100] Problem 1: Some of the embodiments discussed herein relate to overhead in multi-AP transmission. With a multi-AP communication network, data can be transmitted from multiple APs to STAs simultaneously in the downlink, and data from STAs can be transmitted to multiple APs simultaneously in the uplink. In order to achieve such capabilities, STAs may need to be associated with multiple APs to achieve multi-AP transmission / reception simultaneously. The traditional AP-STA association protocol does not facilitate this because each STA can only be associated with one AP at a given time. Therefore, it may be desirable to develop a more efficient method for achieving multi-AP association.

[0101] Question 2: In some embodiments, multiple APs may collaborate to achieve higher peak throughput and increased efficiency and better BSS edge coverage (e.g., a multi-AP solution may be used to reach STAs in the cell edge). Preferably, some embodiments may address fairness and coverage of cell edge STAs. In a single-AP scenario, a STA may typically only listen to beacons from one AP, and for STAs at the edge of the coverage area, it may be difficult for the AP to decode normal beacon transmissions. Therefore, for multi-AP capabilities in the network, it may be desirable to provide solutions and mechanisms for extending the coverage of beacon transmission and reception. Figure 7 An exemplary scenario of beacon transmission coverage of cell edge STAs is shown. Figure 7 In the figure, the arrows indicate the STAs at the edge. In some implementations, the STAs can be implemented by joint transmission. In some implementations, the STAs may or may not be able to receive normal beacons.

[0102] Question 3: Some embodiments discussed herein relate to time synchronization (e.g., TSF) when receiving from multiple APs. In multi-AP transmissions, if a cell edge STA receives a joint transmission of a beacon frame from all APs in a virtual AP set simultaneously, the time synchronization function at the STA may behave in the same manner as a traditional STA. However, each AP has its own busy / idle medium state at the target beacon transmission time (TBTT), and not all APs may be able to perform a joint transmission at the desired time. In this case, the transmission times of beacon frames from different APs may be staggered. Even if a joint transmission can be transmitted from all APs in a virtual AP set / multi-AP set, a cell edge STA may still not be able to receive the joint transmission (e.g., due to local interference from an OBSS). In this case, it may be advantageous for the APs to intentionally stagger their beacon transmissions in time for increased diversity (e.g., in terms of interference).

[0103] When beacons are transmitted at different times, the timestamp fields therein should be different. Given that the rest of the content is the same between beacons in the same BI, the different timestamp fields create different PSDUs. This prevents the PHY method from combining the signals efficiently.

[0104] In some embodiments, to overcome this, all APs may use the timestamp of a particular beacon frame (e.g., the first beacon transmitted in the BI) among one or more beacon frames transmitted by them. However, this may require that both the AP and the STA be able to at least detect the transmission of that beacon frame, and may require that the AP be able to decode that particular frame. This approach may result in multiple beacons transmitted at different times. However, if the STA cannot detect the first beacon (e.g., due to a collision), the timing synchronization function (TSF) is not updated in that beacon interval (BI), or it may be updated based on a second beacon or a later beacon. This may prevent a time-diverse object from transmitting multiple beacons in time, for example, due to this weakness in the particular transmission at the moment of the timestamp.

[0105] Question 4: Some embodiments discussed herein relate to multi-AP spatial piercing. Multi-AP transmission and reception may involve transmitting to and receiving a group of APs from a STA. In some cases, all APs in the group may not necessarily participate in a particular transmission to or reception from a STA. In some implementations, a STA may favor an AP group in a dynamic AP selection scheme such that only a subset of APs is utilized.

[0106] The following description will first describe the method and process for solving the above-mentioned problem 1. That is, the method and process disclosed in this article solve the problems discussed above related to the overhead in multi-AP transmission. In order to enable multi-AP transmission, multiple APs or AP groups can form a "virtual AP" with a shared virtual basic service set identifier (vBSSID) and / or a virtual service set identifier (vSSID). STA can use vBSSID and / or vSSID to associate with the AP group without knowing that it is an AP group. Figure 8 and Fig. 9 An exemplary virtual AP architecture is shown. Figure 8 An architecture is shown in which a STA can be associated with an AP in a traditional manner or with an AP group via a virtual AP. Fig. 9 An architecture is shown in which a STA is associated with an AP group only via a virtual AP.

[0107] exist Figure 8 In the example of , each AP can have its own BSS. In addition, an AP group can have a virtual AP. A STA can be associated with a traditional single AP or with a virtual AP. Figure 8 As shown, those STAs located at the edge of the BSS coverage area may be associated with the virtual AP, and those STAs not located at the BSS coverage area may be associated with the AP in a traditional manner.

[0108] exist Fig. 9 In the example of , each AP may not have its own BSS. An AP group may have a virtual AP. A STA may be associated with a virtual AP. In the case where multi-AP spatial piercing is allowed, a STA may not always communicate with all APs in a virtual AP group; instead, it may communicate with a subset of APs, and the remaining APs in the group may be considered pierced.

[0109] A STA associated with a virtual AP may have an association identifier (AID) assigned by the virtual AP. The AP group may use the AID to reference the STA. In the case where a large number of STAs are associated with a virtual AP, the number of bits representing the AID may be increased. In some embodiments, a basic AID and an AID extension may be used to uniquely represent a STA in a BSS. The basic AID may be the same size as the current AID discussed above, and if the number of STAs in the BSS is greater than a threshold, an AID extension may be used.

[0110] In DL virtual AP transmission from a virtual AP to a STA, traffic to the STA may be delivered to all relevant APs. The relevant APs may include all APs in a virtual AP group, or a subset of APs used to communicate with the STA. In this way, traffic may be ready to be transmitted from multiple APs to the STA. It should be noted that the above embodiments of DL virtual AP transmission are given by way of example only, and they are not intended to be exclusive or to limit the present application. DL virtual AP transmission may be implemented in any other available manner as long as they can follow the principles and guidelines discussed above.

[0111] In a UL virtual AP transmission from a STA to a virtual AP, a packet transmitted from the STA (e.g., a received physical layer convergence protocol (PLCP) protocol data unit (PPDU)) may be received by all or a subset of the relevant APs. Each AP may partially process the packet and may pass the packet to the backhaul, where more PHY layer processes may be performed at the backhaul. In some embodiments, each AP may recognize that reception may involve multiple APs, and accordingly, the AP may pass the packet to the backhaul. The backhaul may perform combination and decoding of all received valid packets. In some embodiments, each AP may recognize that reception may involve multiple APs, and accordingly, the AP may perform channel estimation and demodulation, and pass the demodulated soft bits (e.g., log likelihood ratio (LLR)) to the backhaul. The backhaul may perform LLR combination and channel decoding. In some embodiments, each AP may recognize that reception may involve multiple APs, and the AP may attempt to detect a packet (e.g., PPDU) and decode it. If the AP successfully detects and decodes the packet, the AP may pass the decoded MAC packet to the backhaul; otherwise, the AP may pass the received packet or demodulated soft bits to the backhaul. It should be noted that the above embodiments of UL virtual AP transmission are given by way of example only, and they are not intended to be exclusive or to limit the present application. UL virtual AP transmission can be implemented in any other available manner as long as they can follow the principles and guidelines discussed above.

[0112] The above figures and descriptions may assume a backhaul connection between APs. However, the APs may be connected and controlled by a central controller or in any suitable manner. In the case of a central controller, the backhaul may be replaced by the central controller. The connection may be wired or wireless. In the case of a wireless connection, the connection may share the same band / channel as the BSS band / channel, or may use a different band / channel.

[0113] The following technical solutions are directed to solving the above problems 1 and 2. That is, some embodiments disclosed below include multi-AP active scanning to solve the above problems 1 and 2. The exemplary multi-AP active scanning process may be performed according to one or more of the following solutions.

[0114] An AP (which may be part of a multi-AP set SSID, where the AP may be a master AP or a slave AP) may include one or more of the following in its beacon, short beacon, FILS discovery frame, and / or (broadcast) probe response: a virtual BSSID, SSID, multi-AP beacon scheduling, preferred scanning method, and / or members of the same multi-AP set. The above information will be further described as follows.

[0115] The virtual BSSID may represent the entire multi-STA set SS. The STA may use the virtual BSSID to send a probe request or an authentication or association request in order to obtain information or authenticate and / or associate with the multi-STA set SS.

[0116] The SSID may represent the entire multi-STA set SS. The STA may use the SSID to send a probe request or an authentication or association request in order to acquire information or perform authentication and / or association with the multi-STA set SS.

[0117] Multi-AP beacon scheduling may indicate that one or more APs within a multi-AP set SS may transmit beacons or multi-AP beacons, FILS discovery frames, and probe responses concurrently or sequentially. Multi-AP beacon scheduling may be indicated according to an offset with a TSF timer (which may also be included in a probe response) or an offset with the end of the current frame. Multi-AP beacon scheduling may also include or may alternatively include a scheduling of triggered multi-AP beacon frames and / or multi-AP probe response frames or FILS discovery frames.

[0118] The preferred scanning method may indicate a preferred method for scanning, including multi-AP active scanning, passive scanning, single AP active scanning, etc. Members of the same multi-AP set may indicate one or more APs within the same multi-AP set. Alternatively or in addition, the AP may include this information in a reduced neighbor report, or in a co-located or co-hosted AP, for example, by indicating it within the same multi-AP set SS.

[0119] It should be noted that the above information that may be included in the AP's beacon, short beacon, FILS discovery frame and / or (broadcast) probe response is given by way of example only, and is not intended to be exclusive or to limit the present application. Any other available information may be included, as long as it can follow the principles and guidelines discussed above.

[0120] The above information may be included in one or more of the following fields or elements: Multi-AP element, Reduced Neighbor Report, Neighbor Report, Multi-Band Report, 6GHz Discovery Element, and / or Out-of-Band Assisted Discovery Element. The information may be transmitted in a frequency band or frequency channel other than the frequency band or frequency on which the beacon is transmitted. Other neighboring APs or BSSs may include such information overheard from other AP information, such as in their own Multi-AP element, Reduced Neighbor Report, Neighbor Report, or other fields.

[0121] The STA may initiate a multi-AP active scanning process by sending a detection request frame that may include a multi-AP capability element. The multi-AP capability element may include a list of multi-AP capabilities that the STA can implement in the uplink and / or downlink, for example, multi-AP joint transmission, multi-AP MIMO, multi-AP MU-MIMO, multi-AP HARQ, multi-AP dynamic AP selection, multi-AP space piercing, multi-AP space zeroing, etc. The multi-AP capability element may also indicate how many APs the STA can support concurrently.

[0122] The probe request frame may include an SSID, a BSSID, or a virtual BSSID. The SSID, BSSID, or virtual BSSID may be used to identify a multi-AP set. The scanning STA may have been through a previous association, or through pre-acquired knowledge (such as through a FILS discovery frame), or from a neighbor report or a reduced neighbor report, or through a 6GHz discovery element, or an auxiliary discovery element that may be transmitted by another AP and / or a co-hosted or co-located AP, or on a different channel or a different frequency band. The probe request frame may include an indication that it is requesting a multi-AP probe response or a multi-AP response (which may be included in a multi-AP capability element or a multi-AP request element).

[0123] In the case where an AP is part of a multi-AP set SSID, where the AP can be a master AP or a slave AP, it can respond to the probe request in the following manner.

[0124] If the probe request includes a multi-AP capability element and / or a multi-AP request element, and if the probe request is not addressed to represent the SSID and / or virtual BSSID of the entire multi-AP set SS, the AP may respond by including a probe response frame that may include a multi-AP element. The multi-AP element may include all information about multiple APs in the same set, which may include one or more of the following: virtual BSSID, SSID, multi-AP beacon scheduling and / or preferred scanning method. The above information that may be included in the multi-AP element will be further described as follows.

[0125] The virtual BSSID may represent the entire multi-STA set SS. The STA may use the virtual BSSID to send a probe request or an authentication or association request in order to obtain information or authenticate and / or associate with the multi-STA set SS.

[0126] The SSID may represent the entire multi-STA set SS. The STA may use the SSID to send a probe request or an authentication or association request in order to acquire information or perform authentication and / or association with the multi-STA set SS.

[0127] Multi-AP beacon scheduling may indicate that one or more APs within a multi-AP set SS may transmit beacons or multi-AP beacons, FILS discovery frames, and probe responses concurrently or sequentially. Multi-AP beacon scheduling may be based on an offset of a reference TSF timer (which may also be included in a probe response) or an offset of the end of a reference current frame. It may also be a scheduling of a triggered multi-AP beacon and / or multi-AP probe response or FILS discovery frame.

[0128] The preferred scanning method may indicate a preferred method for scanning, including multi-AP active scanning, passive scanning, single AP active scanning, and the like.

[0129] It should be noted that the above information that may be included in the multi-AP element is given by way of example only and is not intended to be exclusive or to limit the present application. Any other available information may be included as long as it can follow the principles and guidelines discussed above.

[0130] If the probe request includes a multi-AP capability element and / or a multi-AP request element, and the probe request is addressed to represent the entire multi-AP set SSID and / or virtual BSSID, the AP may respond by a probe response frame or a trigger frame, for example, as described below.

[0131] If the AP responds by a probe response frame, the probe response frame may include multiple AP elements. The multiple AP elements may include all information about multiple APs in the same set, which may include one or more of the following information as described above. It may then trigger one or more probe responses or beacon frames transmitted by one or more APs in the same multi-AP set SS. In addition or alternatively, the AP may trigger the concurrent transmission of multi-AP beacons or multi-AP probe response frames that can be addressed to the detection STA or broadcast address. The triggering of concurrent or sequential multi-AP beacons and / or probe responses may follow the multi-AP beacon scheduling. If the AP responds to one or more APs in the same multi-AP set by triggering a frame, the AP may trigger the concurrent transmission of multi-AP beacons or multi-AP probe response frames that can be addressed to the detection STA or broadcast address. The triggering of concurrent or sequential multi-AP beacons and / or probe responses may follow the multi-AP beacon scheduling. Multi-AP beacons or multi-AP probe response frames may be shared by the master AP to all other APs in the same multi-AP set SS. It should be noted that the above-mentioned ways of responding by means of a detection response frame or a trigger frame are given only by way of example, and they are not intended to be exclusive or to limit the present application. Any other available ways may be used, as long as they can follow the principles and guiding principles discussed above of the present application.

[0132] After receiving a probe response frame that may include multiple AP elements, the STA may follow the instructions included in the probe response frame for further scanning and / or authentication / association. For example, if the preferred scanning method is indicated as multi-AP active scanning, the STA may send a probe request to the SSID and / or virtual BSSID representing the multi-AP set SS, which may also include multi-AP elements and / or multi-AP request elements. If the preferred scanning method is indicated as passive scanning, the STA may follow the multi-AP beacon scheduling to receive one or more beacons, probe responses, FILS discovery frames and / or triggered beacons, probe responses, and FILS discovery frames. If the preferred scanning method is indicated as single AP active scanning, the STA may send a probe / authentication / association request to one or more APs included in the probe response frame or pre-acquired information.

[0133] The following technical solution is directed to solving the above-mentioned problems 1 and 2. Some embodiments disclosed below include multi-AP beacons. Multi-AP repeated beacon frames can be transmitted from an AP group. In some embodiments, it is assumed that multiple APs can be grouped together and that a backhaul connection is available between multiple APs. In some embodiments, multiple APs or AP groups can form a virtual AP, and when they transmit multi-AP repeated beacon frames, the APs can share a public virtual BSSID (vBSSI) and / or a virtual SSID (vSSID). In some embodiments, multiple APs can form a group, and the master AP can control the group, or a central controller can control the group. The AP group can use a public BSSID assigned by the master AP or a multi-AP central controller to transmit multi-AP repeated beacons.

[0134] The multi-AP repeated beacons transmitted from the AP group may have the same MAC body and modulation and coding scheme so that the STA can combine the received signals. The indicator may indicate repeated transmission so that the receiver can combine them. For example, the multi-AP repeated transmission field may be set in the PLCP header or MAC header or beacon frame so that the receiving STA can combine the received signals.

[0135] exist Figures 10 to 14 Multiple implementations of multi-AP beacon transmission are shown in FIG. The following description will describe each of these implementations in detail.

[0136] Fig.10 Multiple AP repetitive beacons are shown transmitted sequentially in different time slots. In this example, each AP can still transmit its own beacon for its BSS, which is shown as a normal beacon in the figure, so that the STA can choose to associate with those individual APs first, and depending on its ability to support multi-AP transmission, it can decide whether to associate with the multi-AP group later. Fig.10 As shown, AP1 may transmit a normal beacon B1; AP2 may transmit a normal beacon B2; AP3 may transmit a normal beacon B3 and AP4 may transmit a normal beacon B4. Multiple APs repeat beacons ( Fig.10 B) shown in can be transmitted sequentially by the AP group.

[0137] In some embodiments, the leading AP may start multiple APs repeating beacon transmissions. The remaining APs in the group may follow xIFS (any inter-frame spacing, such as short IFS (SIFS), point cooperation function (PCF) IFS (PIFS), distributed cooperation function (DCF) IFS (DIFS), etc.). When an AP joins the group, the transmission order may be negotiated. Alternatively, the transmission order may be determined by the AP's geometric location, MAC address, time of joining the group, etc.

[0138] Fig.11FIG. 4 shows multiple AP repeated beacons transmitted concurrently. In this example, each AP can still sequentially transmit its own normal beacon for its BSS, which is transmitted in Fig.11 In FIG. 1 , multiple APs are shown as normal beacons (e.g., B1, B2, B3, and B4). Fig.11 B) shown in FIG. 1 may be transmitted concurrently by a group of APs. The transitions of multiple AP repeating beacons may be identical and well synchronized so that STAs can decode them.

[0139] Fig.12 Another method is shown in which a leading AP (e.g., AP1) may first start a multi-AP repeated beacon transmission. The remaining APs in the group may concurrently transmit multi-AP repeated beacon frames within the xIFS duration after receiving the leading AP transmission. In this method, the leading AP transmission may be regarded as a trigger frame for triggering multi-AP concurrent beacon transmission. In this method, the APs in the group may sequentially transmit their own normal beacons (e.g., B1, B2, B3, and B4), such as Fig.12 shown.

[0140] Fig.13 FIG. 4 shows a case in which a leading AP (eg, AP1) can transmit a multi-AP beacon trigger frame (ie, Fig.13 All APs in the group may concurrently transmit a multi-AP repetitive beacon frame within the xIFS duration just after the trigger frame.

[0141] If multiple channels may be idle, multiple AP repetitive beacons may be transmitted through the multiple channels. Both sequential transmission and concurrent transmission may be summarized as multi-channel transmission situations. Fig.14 An example of such a sequential transmission scheme is shown in FIG. Fig.14 As shown, each AP can still transmit its own normal beacon for its BSS, which is Fig.14 In this example, multiple AP repeated beacons can be transmitted sequentially on two channels in a non-overlapping format. AP1 can be shown as normal beacons, i.e., B11, B12, B21, B22, B31, B32, B41, and B42. Fig.14 In the first time slot shown, a multi-AP repetitive beacon is transmitted through channel 1, and AP2 may transmit the multi-AP repetitive beacon through channel 2 in the first time slot. Similarly, AP3 and AP4 transmit their multi-AP repetitive beacons through channel 1 and channel 2, respectively, in the second time slot. Alternatively, the leading AP may need to transmit a frame just before the set of multi-AP repetitive beacon transmissions to synchronize the APs. The frame may be a trigger frame or a beacon frame. It should be noted that reference Fig.14The above embodiments shown are given by way of example only, and are not intended to be exclusive or to limit the present application. Multiple APs may transmit their multi-AP repetitive beacons in any other different manner associated with different time slots and different channels. For example, AP1 may transmit its multi-AP repetitive beacon through channel 1 in the second time slot, and AP2 may transmit its multi-AP repetitive beacon through channel 2 in the second time slot, and thus AP3 may transmit its multi-AP repetitive beacon through channel 1 in the first time slot, and AP4 may transmit its multi-AP repetitive beacon through channel 2 in the first time slot.

[0142] At the end of the association process, the STA may be associated with one AP group in one channel and another AP group in another channel. Some of those APs in both groups may be physically identical. The STA may need to report back to the network which APs they can hear on which channel. The network can then use the available resources (including physical APs and channels) to complete the association process.

[0143] In some such methods, it may be assumed that each of the AP group may be available to transmit beacons simultaneously. In some such methods, it may be assumed that a lead AP may transmit and reserve the channel, and the remaining APs may follow the transmission after an xIFS duration.

[0144] In the case where not all APs in a group are available to transmit sequentially or concurrently (e.g., due to hidden nodes or untruncated transmissions), a method such as Fig.15 As shown in the method). Fig.15 As shown, the repetitive beacon transmission interval may be predefined or predetermined and known by the STA and AP. Once available, all APs in the group may transmit multi-AP repetitive beacons within the repetitive beacon transmission interval. In some embodiments, the APs in the group may not transmit traditional beacons (their own beacons) in the interval. The repetitive beacon transmission interval may be defined by one or more methods (such as static methods, semi-static methods, and / or dynamic methods). These three methods will be described with reference to the detailed embodiments below.

[0145] In a static approach, a repetitive beacon transmission interval may be defined by a fixed starting position and duration. The starting position and duration of the interval may be predefined or predetermined, or announced in a previous multi-AP repetitive beacon. In one embodiment, the duration may be defined using real-time units such as microseconds. In another embodiment, the duration may be defined as a fraction of a beacon interval. A beacon interval may be defined as the duration between two different sets of repetitive beacons, such as Fig.15 shown.

[0146] In a semi-static method, a repeated beacon transmission interval may be defined by a fixed duration but by a dynamic starting position. That is, the starting position when an AP may transmit its first frame in a multi-AP repeated beacon transmission sequence may not be a fixed position. The AP may be a leading AP. The first frame may be a beacon frame or a trigger frame. The duration of the repeated beacon transmission interval may be predefined or predetermined, or announced in a previous multi-AP repeated beacon.

[0147] In a dynamic approach, a repeated beacon transmission interval may be defined as having both a dynamic starting position and a dynamic duration. The starting position may be the time at which the AP transmits its first frame in a multi-AP repeated beacon transmission sequence. Due to the density of STAs in a BSS or virtual BSS, the interval duration may be adjustable. For example, in a densely deployed system, more transmissions and hidden nodes may be expected, and longer intervals may be beneficial. Otherwise, shorter intervals may be used. The duration of the interval may be announced in a previous multi-AP repeated beacon. In the absence of an explicit signaling duration, STAs and APs may reuse the same duration.

[0148] It should be noted that the above three exemplary methods for defining a repetitive beacon transmission interval are given by way of example only, and they are not intended to be exclusive or to limit the present application. There may be other available methods for defining a repetitive beacon transmission interval, as long as these methods follow the principles and guidelines discussed above.

[0149] The STA may expect to receive repeated beacons within a time interval. In some specific implementations, the time interval may be predefined / predetermined / signaled by the AP. In some specific implementations, the time interval may be determined based on the STA process. The time interval may be defined as having a starting position (t0) and a duration (T). The duration may be determined, for example, using a previously received repeated beacon, or may be predefined, for example, by a standard. In the case of a fixed position, the starting position may be determined, for example, by a previously received repeated beacon or predefined by a standard. In the case of a dynamic starting position, the starting position may be determined when the STA detects the first frame of a repeated beacon transmission. For example, in the case of a dynamic starting position, the STA may have encountered an opportunity to miss the detection of the starting position (e.g., t1). The STA may then monitor the repeated beacon transmission interval [t1, t1+T] from the missed detected starting position.

[0150] The STA may start a repeated beacon timer at the starting position t0. If the timer is less than the duration T, the STA may continue to monitor the channel for repeated beacon transmissions. The STA may detect frame transmissions. By checking the PLCP header or control notice or other types of separately encoded parts of the frame, the STA may obtain the transmitter identity, such as MAC address, compressed MAC address, BSSID, compressed BSSID, BSS color, etc. The STA may recognize that this may be a repeated transmission or a HARQ transmission, for example, by detecting a repeated transmission field set to 1. If this is the first frame in the interval from the same transmitter ID, the STA may decode it. If the decoding fails, the STA may save it in a buffer. If this is not the first frame from the same transmitter ID, the STA may combine it with the data stored in the buffer. If it is not successfully decoded, the STA may save the combined data in the buffer and continue to monitor the channel. If the timer is greater than the duration T, the STA may clear the buffer.

[0151] STAs that can be associated with a BSSID carried by a multi-AP repeated beacon can be considered as STAs that can communicate with an AP group or a virtual AP. In repeated beacon transmissions, the AP group or virtual AP can select a modulation and coding scheme (MCS) that can be supported by all STAs. The selected MCS can be higher than the lowest supported MCS. Although the various methods of this article are discussed with respect to repeated beacon transmission schemes, similar ideas can be applied to detection response frame and association response frame transmissions. Information elements and fields have been discussed in other embodiments. Note that in Figures 10 to 14 In each of the figures in , each AP in the group can transmit one multi-AP repeated beacon in the beacon interval. However, this can be easily extended to the general case, where each AP can be allowed to transmit 0 to N repeated beacons in the beacon interval. In the exemplary case, the AP group can contain only one AP, and the AP can still transmit multiple repeated beacons in the beacon interval. Note that the terms repeated beacon, multi-AP repeated beacon, and multi-AP beacon are used interchangeably. Figures 10 to 14 In the example, beacon frames can be used to show repeated transmissions from multiple APs. The scheme can be easily extended by using other control / management / data frames. For example, beacon frames can be replaced by probe frames, highly reliable data transmission frames, etc.

[0152] The following technical solutions are directed to solving the above problem 3. Some embodiments solve the TSF of repeated beacons. Some such embodiments can solve the time synchronization problem when receiving from multiple APs. In this example, it is assumed that the APs in the virtual AP set synchronize their TSFs and use a multi-AP repeated beacon transmission process.

[0153] In some embodiments, the TSF may be signaled in the preamble of each beacon so that each repetition has its own self-contained TSF timer. The timestamp field may be 8 bytes, which may increase the preamble size. The increased size may reduce the range and reliability of the preamble, thereby preventing cell edge STAs from detecting repeated beacons. Therefore, in some embodiments, the signal target beacon transmission time (TBTT) is in the beacon frame rather than in the timestamp of the beacon. The preamble is used to signal the time offset between the repeated beacon and the TBTT. In this method, the preamble of the repeated beacon_i may provide the receiver with an offset between the TBTT and the time of the beacon_i as t_i. After a single or combined multiple repeated beacons, the contents of the beacon are decoded, and the TBTT value is known to the receiver. Based on t_i and the internal clock of the receiver when receiving beacon_i, the receiver will be able to map the TBTT to its own internal clock.

[0154] Some such embodiments have the following advantages: each repeated beacon in the same BI has the same TBTT value in the payload, and therefore, repeated beacons (e.g., such as HARQ transmissions) can be combined. In addition, repeated beacons of the same BI must be transmitted within the beacon window after the TBTT, so the range of t_i is defined by the beacon window or the repeated beacon transmission interval defined in the above paragraph for multi-AP beacons. The window may be smaller than the range of timestamp values. Therefore, the offset t_i may be more suitable for carrying in the preamble of each repeated beacon. t_i can be conceptualized as the least significant bit (LSB) or the most significant bit (MSB) of the 64-bit timestamp of each repeated beacon. For example, if the beacon window is 10ms, the exemplary t_i may be approximately 14LSB of the timestamp. Fig.16 Exemplary TBTT / beacon windows and t_i are shown. It should be noted that the above beacon windows and timestamps are given by way of example only, and they are not intended to be exclusive or limiting to the present application.

[0155] Some embodiments also include optimizations for further reducing the information representing t_i. In some embodiments, t_i is quantized with a granularity of Δt. For example, if Δt=64us and the beacon window is 10ms, t_i can be represented by 8 bits in the preamble. This can produce ambiguity (e.g., 64us ambiguity in this example). One method for resolving this ambiguity is to require the AP to always start or end repeated beacon transmissions at the boundary of the Δt interval, and t_i indicates the time from TBTT to the start or end of the repeated beacon. The start or end at the Δt interval each presents various challenges.

[0156] Starting at a boundary may limit channel access opportunities, for example, because a boundary may coincide with a medium busy period, while a non-boundary duration coincides with a medium idle time. In order to increase channel access opportunities, in some embodiments, a reservation signal may be used. For example, a reservation signal (or a dummy signal) may be inserted before (e.g., immediately before) a real beacon transmission so that the channel is occupied. A real beacon transmission may start at the boundary of the Δt interval. However, the length of the reservation signal may not be an integer multiple of an OFDM symbol. Similarly, the end at a boundary may require the application of padding, and the padding may not be an integer multiple of an OFDM symbol.

[0157] Fig.17 An exemplary method for resolving this ambiguity while keeping the reserved / filler signals as integer multiples of OFDM symbols is shown. Unlike arbitrary length busy signals that the receiver cannot exploit, these symbols can be used to carry extra parity bits or training fields to protect the PPDU.

[0158] like Fig.17 As shown, padding is shown at the end of the PPDU. Alternatively, padding may be placed at the beginning of the PPDU to serve as a reserved signal. Alternatively, padding may be placed in a predefined position in the PPDU. Padding can be used to make the end (or start) of the PPDU within 1 OFDM symbol at the nearest Δt interval boundary. In some embodiments, the PPDU length signaled in the preamble is the length to the end of the padding. The additional information in the padding may include additional parity bits or training symbols. In some embodiments, the PPDU length signaled in the preamble is the length to the end of the padding, but there is no actual transmission signal in the padding.

[0159] To resolve the ambiguity within the OFDM symbol, one or more pairs of short training field (STF) or long training field (LTF) symbols may be used, for example, one without any phase adjustment and the other with a linear phase shift corresponding to the time offset between the end of the filling symbol and the nearest Δt interval boundary. Based on the linear phase shift difference between the two symbols, the receiver can determine the time of the nearest Δt interval boundary according to the end time of the filling. Starting from the time of the nearest Δt interval boundary, the receiver can use the quantized t_i from the preamble (which is an integer multiple of Δt, 4Δt in the following example) to derive the TBTT. In some embodiments, the filling duration is fixed and can be one or more pairs of special and / or longer LTFs with T_sym=Δt. In this case, the PPDU may no longer need to be filled with an integer number of normal OFDM symbols to the nearest Δt interval boundary. This can achieve a direct estimate of the packet start / end time for the nearest Δt interval boundary. In various embodiments, some time-related parameters such as offset t_i and quantized t_i are included in the preamble. Alternatively, they may be included in any other separately encoded and CRC-protected parts.

[0160] The following technical solutions are directed to solving the above-mentioned problem 4. Some embodiments solve multi-AP space piercing transmission. In some embodiments, multi-AP transmission and reception may involve transmitting to and receiving an AP group from a STA. In other embodiments, multiple APs may form an AP group or a virtual AP to communicate with the STA. It may not be necessary for all APs in the group to join a specific transmission to the STA or reception from the STA, or it may not be effective to use all APs in the group to communicate with the STA. In some specific implementations, the STA may favor an AP group in a dynamic AP selection scheme (e.g., a multi-AP space piercing transmission scheme) so that only a subset of APs is utilized. In other words, a multi-AP space piercing transmission scheme may be used, for example, to enable a subset of APs in the group to transmit to and / or receive from the STA. In this case, it can communicate with a subset of APs, and the remaining APs in the group can be considered to be pierced. That is, some APs in the group that will not communicate with the STA can be considered to be "pierced" from the communication in the spatial domain.

[0161] To achieve spatial piercing transmission, an AP group or virtual AP may determine a subset of APs to be used for communication with a STA. In some embodiments, a modified multi-AP repeated beacon transmission scheme is used to enable the STA to measure the signal power received from each AP and provide feedback to the AP group or virtual AP. The following description will refer to Fig.18 and Fig.19Describe such a multi-AP repeated beacon transmission scheme according to a preferred embodiment of the present application. Note that we use a multi-AP repeated beacon transmission scheme as an example. It can be extended to a multi-AP repeated transmission scheme by using any other frame (such as a management frame, a control frame, or a data frame) instead of a beacon frame.

[0162] Fig.18 FIG. 2 shows the overall process of the multi-AP repeated beacon transmission scheme according to the implementation scheme of the present application. Fig.18 As shown, it is assumed that AP1, AP2, AP3 and AP4 cooperate to form a multi-AP transmission / reception group or a multi-AP transmission set or a virtual AP. Each AP can transmit a common information portion (ie, Fig.18 The common part shown) and the AP-specific information part (i.e., Fig.18 Therefore, if Fig.18 As shown, there are a total of four common information parts and a total of four AP-specific information parts. The common information part is transmitted, or assumed to be transmitted (and received) from multiple APs, and may be the same so that it can be combined and decoded at the STA. The AP-specific information part that can be transmitted (and received) is different from AP to AP so that the STA can identify the specific AP that transmits the AP-specific information part or perform AP-specific measurements (discussed below). Based on the decoding of the common information part and the AP-specific information part, the STA can provide feedback information to the multi-AP transmission set (i.e., multi-AP group) to assist in future multi-AP transmissions; for example, AP and STA selection, multi-AP scheme, MCS, power, etc. The common information part and the AP-specific information part can be separately encoded and protected using different CRCs.

[0163] It should be noted that Fig.18 Only the overall process of the exemplary multi-AP repeated beacon transmission scheme is shown, and its detailed implementation will be referred to below. Fig.19 In the present application, unless otherwise indicated, the terms "common information part" and "common part" may be used interchangeably, and the terms "AP specific information part" and "AP specific part" may be used interchangeably.

[0164] It should be noted that in some embodiments, the common information portion may also be referred to as a "common beacon" and the AP-specific information portion may also be referred to as an "AP-specific beacon". A repeating beacon may actually be transmitted in two separate parts: one for the common information portion and another for the AP-specific information portion. For example, in a scenario, the common information portion and the AP-specific information portion may be transmitted separately. In this case, the common information portion may be referred to as a "common beacon" and the AP-specific information portion may be referred to as an "AP-specific beacon".

[0165] Preferably, in each repeating beacon, the common information portion and the AP-specific information portion may be transmitted together with an interframe space therebetween. In this case, the common information portion may also be referred to as a "common beacon," and the AP-specific information portion may also be referred to as an "AP-specific beacon." Thus, the terminology that may be used for the different portions of a repeating beacon (i.e., the common portion and the AP-specific portion) may vary according to different implementations.

[0166] Fig.19 FIG. 1 shows a flow chart of a method 1900 for multi-AP transmission according to the present application. Fig.19 As shown, method 1900 includes: at 1901, receiving multiple repeated beacons, one repeated beacon comes from each of multiple APs, each of the multiple repeated beacons includes a common information part and an AP-specific information part; at 1902, decoding at least one of the multiple common information parts or a combination of one or more common information parts to obtain a first parameter; at 1903, decoding the multiple AP-specific information parts to obtain multiple second parameters, each second parameter is associated with one of the multiple APs; at 1904, generating feedback based on the first parameter, the multiple second parameters and the number of multiple APs; and at 1905, transmitting the feedback to at least one of the multiple APs.

[0167] Therefore, a WTRU according to the present application may include: a transceiver configured to receive multiple repeated beacons, one repeated beacon from each of a plurality of APs, each of the multiple repeated beacons including a common information portion and an AP-specific information portion; and a processor configured to decode at least one of the multiple common information portions or a combination of one or more common information portions to obtain a first parameter; decode the multiple AP-specific information portions to obtain multiple second parameters, each second parameter being associated with one of the multiple APs; and generate feedback based on the first parameter, the multiple second parameters and the number of the multiple APs, wherein the transceiver is further configured to transmit the feedback to at least one of the multiple APs.

[0168] The following description will describe the above process from 1901 to 1905 and the components of the WTRU in detail. Some embodiments may also involve Fig.18 Examples shown for reference.

[0169] The process at 1901 will be discussed as follows. Fig.19As shown, method 1900 may include, at 1901, receiving a plurality of repeated beacons, one repeated beacon from each of a plurality of APs, each of the plurality of repeated beacons including a common information portion and an AP-specific information portion. Thus, a transceiver may be configured to receive a plurality of repeated beacons, one repeated beacon from each of a plurality of APs, each of the plurality of repeated beacons including a common information portion and an AP-specific information portion.

[0170] Repeated beacons may also be referred to as multi-AP repeated beacons or multi-AP repeated beacon frames. Figures 10 to 14 As discussed, multiple AP repeated beacons may be transmitted from an AP group. In some embodiments, multiple APs or AP groups may form a virtual AP, and when they transmit multiple AP repeated beacon frames, the APs may share a public virtual BSSID (vBSSI) and / or a virtual SSID (vSSID) and / or a virtual BSS color. In some embodiments, multiple APs may form a group, and the master AP may control the group, or the central controller may control the group. The AP group may transmit multiple AP repeated beacons using a public BSSID assigned by the master AP or multiple AP central controller.

[0171] Multiple APs can repeat beacons Figures 10 to 14 For example, multiple AP repeated beacons may be transmitted sequentially in different time slots, such as Fig.10 As shown. Multiple APs can repeat beacons as follows Fig.11 The concurrent transmission is shown. Fig.12 In the illustrated embodiment, the leader AP may first initiate a multi-AP repetitive beacon transmission, and the remaining APs in the group may concurrently transmit multi-AP repetitive beacons within the xIFS duration after receiving the leader AP transmission. Fig.13 In the illustrated embodiment, the lead AP may transmit a multi-AP beacon trigger frame, and then all APs in the group may concurrently transmit multi-AP repetitive beacons within the xIFS duration just after the trigger frame.

[0172] The multi-AP repeated beacon transmitted from the AP group may have a common information part including a MAC body and a modulation and coding scheme, so that the STA can combine the received signal. A special indicator may be required to indicate repeated transmissions so that the receiver can combine them. For example, in the PLCP header or MAC header or beacon frame, a special indicator (such as a multi-AP repeated transmission field) may be set so that the receiving STA can combine them.

[0173] In some embodiments, in an AP group, the public information portion may include the same information. For example, a public beacon may carry the information discussed above, such as a virtual BSSID, SSID, multi-AP beacon scheduling, a preferred scanning method, members of the same multi-AP group, and other information typically carried in a beacon frame. The information carried by the public beacon may be understood with reference to the above paragraphs regarding the multi-AP scanning scheme. It should be noted that the above information in the public information portion is given by way of example only, and they are not intended to be exclusive or to limit the present application. The public information portion may include any available information based on the above principles of the present patent application, as long as the information can contribute to the implementation of such principles.

[0174] The AP-specific information portion may include one or more of the following fields: a field for AP ID, a field for the total number of repeated beacons, a field for repeated transmission ID, decoding parameters (e.g., decoding metrics), and / or a field for the number of remaining repeated beacons to be transmitted. The AP ID field may be used to uniquely identify an AP / virtual AP in an AP group. The total number of repeated beacons field may be used to indicate the number of the total number of repeated beacons. Alternatively, this may be carried in the common beacon portion. The repeated transmission ID field may be set to k to indicate that the current transmission may be the kth repeated transmission in the beacon set. It should be noted that the above fields in the specific information portion are given by way of example only, and they are not intended to be exclusive or limiting to the present application. The AP-specific portion may include any available information / fields based on the above principles of the present patent application, as long as the information / field can help implement such principles.

[0175] The common information part and the AP specific information part can be implemented and transmitted using a variety of different ways. The following description will discuss some preferred ways for implementing and transmitting the common information part and the AP specific information part.

[0176] In some embodiments, repeated beacons (ie, multi-AP repeated beacons) may be aggregated with normal 802.11 beacons, for example, where each beacon is sent at the TBTT for each AP in a collaborative manner. In this case, the common information portion and the AP-specific information portion may be aggregated with the normal beacon.

[0177] In some embodiments, the repeating beacon may be sent as a single beacon having a common component and an AP-specific component (i.e., a common information portion and an AP-specific information portion). Preferably, the common information portion and the AP-specific information portion may be Figures 10 to 24 The following description will refer to Figures 10 to 24 Discuss those methods further.

[0178] Preferably, in each repeated beacon, the common information part and the AP specific information part can be aggregated together without any inter-frame spacing between them. Fig. 20 The four elements in the diagram are shown in the following four different scenarios.

[0179] In the first scenario, the common information part and the AP specific information part may be transmitted as an aggregated PPDU (A-PPDU) via a separate preamble. Fig. 20 As shown in the first element of , the common information part 2003 can be transmitted together with the traditional preamble code 2001 and the EHT preamble code 2002; the AP specific information part 2006 can be transmitted together with the traditional preamble code 2004 and the EHT preamble code 2005. There is no inter-frame spacing between the common information part 2003 and the AP specific information part 2006. The sequence of the common information part and the AP specific information part shown by the first element is only exemplary. For example, in one embodiment, item 2003 can represent the AP specific information part, and at the same time item 2006 can represent the common information part. It should be noted that Fig. 20 The first element of is given by way of example only and is not intended to be exclusive or limiting to the present application. For example, the common information part and the AP specific information part may be transmitted with a HE / EHT or later version preamble.

[0180] In the second scenario, they may be transmitted via a single legacy preamble but via separate EHT preambles. Fig. 20 As shown in the second element of , the common information part 2013 can be transmitted together with the EHT preamble code 2012; the AP specific information part 2015 can be transmitted together with the EHT preamble code 2014; the common information part 2013 and the AP specific information part can be transmitted together with the traditional preamble code 2011. There is no inter-frame spacing between the common information part 2013 and the AP specific information part 2015. The sequence of the common information part and the AP specific information part shown by the second element is only exemplary. For example, in one embodiment, item 2013 may represent the AP specific information part, and at the same time item 2015 may represent the common information part. It should be noted that Fig. 20 The second element of is given by way of example only and is not intended to be exclusive or limiting to the present application. For example, the common information part and the AP specific information part may be transmitted with a HE / EHT or later version preamble.

[0181] In the third scenario, AP-specific information can be transmitted to the public AP as a control announcement. Fig. 20As shown in the third element of , the AP-specific information part may be carried in the control announcement 2024. The common information part 2023 and the AP-specific information part 2024 may be transmitted together with the traditional preamble 2021 and the EHT preamble 2022. There is no interframe spacing between the common information part 2023 and the AP-specific control announcement 2024. The sequence of the common information part and the AP-specific information part shown by the third element is only exemplary. For example, in one embodiment, item 2023 may represent the AP-specific information part, and at the same time item 2024 may represent the control announcement carrying the common information part. It should be noted that Fig. 20 The third element of is given by way of example only and is not intended to be exclusive or to limit the present application. For example, the common information part and the AP specific information part may be transmitted with the HE / EHT or later version preamble.

[0182] In the fourth scenario, the AP specific information part can be placed in a specific area in the PLCP header. Fig. 20 As shown in the fourth element of , the AP specific information part may be an AP specific header 2033. In this case, the common information part 2034 and the AP specific header may be transmitted together with the traditional preamble 2031 and the EHT preamble 2032. The sequence of the common information part and the AP specific information part shown by the fourth element is only exemplary. For example, in one embodiment, item 2033 may represent a common header as the common information part, and at the same time item 2034 may represent an AP specific information part.

[0183] The above description discusses the separation between the common information part and the AP specific information part. It should be noted that such separation may be necessary to enable the STA to perform repetition, combination, etc. on the common preamble. It should also be noted that the preamble of the AP specific part may have different transmission parameters (e.g., MCS) than the preamble of the common information part. For example, the AP specific information part may be encoded and modulated at a lower data rate so that the STA may be able to decode the part without repetition combination as performed for the common information part.

[0184] Preferably, the common information part and the AP specific information part can be transmitted together with xIFS in between. In such a case, the common information part and the AP specific information part must have separate preambles. Fig.21 An exemplary separation structure of this preferred embodiment is shown. Fig.21 As shown, the common information part 2103 can be transmitted together with the traditional preamble code 2101 and the EHT preamble code; the AP specific information part 2106 can be transmitted together with the traditional preamble code 2104 and the EHT preamble code 2105; there is an xIFS interval between the common information part 2103 and the traditional preamble code 2104. Fig.21 The sequence of the common information part and the AP specific information part shown is exemplary only. For example, in one embodiment, item 2103 may represent the AP specific information part and at the same time item 2106 may represent the common information part. For example, the common information part and the AP specific information part may be transmitted with a HE / EHT or later version preamble.

[0185] Preferably, the common information part and the AP-specific part may be transmitted separately as two different beacons. That is, the common information part may be transmitted as a common beacon, and the AP-specific part may be transmitted as an AP-specific beacon. In this case, each AP may transmit a common beacon and an AP-specific beacon, and the common beacon and the AP-specific beacon may together form a repeating beacon.

[0186] In some embodiments, common beacons and AP-specific beacons may be transmitted separately via different TBTTs.

[0187] In some embodiments, public beacons are grouped together and AP-specific beacons are grouped together. A STA can implicitly identify the AP that sent the public beacon based on its transmission time relative to the AP-specific beacon transmission. Some such embodiments allow the use of normal beacons as AP-specific beacons. The order of beacons can be signaled in the public beacon, and the order can be static, semi-static, or dynamic.

[0188] In some embodiments, it may be desirable to coordinate the transmission of repeated beacons because the APs may be positioned in a manner such that enhanced distributed channel access (EDCA) does not prevent them from transmitting simultaneously, while the STAs require them to transmit at separate times to be able to decode the AP-specific portions of the repeated beacons. To ensure that the AP-specific portions of the repeated beacons do not overlap, a transmission window may be defined and the APs may be allowed to transmit according to their windows (e.g., transmit only within their windows, or not transmit within their windows). Thus, by not allowing multiple windows to overlap each other, the APs may collaborate to ensure that their repeated beacons do not overlap. Thus, both the common portion and the AP-specific portion from the repeated beacons may be successfully decoded. Figure 22 to Figure 23 Two examples of the above-mentioned window are shown. The following description will describe the window in more detail with reference to each example.

[0189] Fig. 22 An example of the above window is shown. In this example, each AP is allowed to transmit repeated beacons only within the window allocated to it. Fig. 22As shown, B1 represents a repeated beacon transmitted by AP1, and AP1 may transmit its repeated beacon only within the B1 window 2201. B2 represents a repeated beacon transmitted by AP2, and AP2 may transmit its repeated beacon only within the B2 window 2202. B3 represents a repeated beacon transmitted by AP3, and AP3 may transmit its repeated beacon only within the B3 window 2203. B4 represents a repeated beacon transmitted by AP4, and AP4 may transmit its repeated beacon only within the B4 window 2204.

[0190] like Fig. 22 As shown, B1 window 2201, B2 window 2202, B3 window 2203, and B4 window 2204 may not overlap with each other. In one embodiment, there may be no time gap between two adjacent windows. In other words, windows assigned to different APs may be connected to each other end-to-end. For example, Fig. 22 As shown, there is no time gap between the B1 window 2201 and the B2 window 2202. The remaining windows can be designed in a similar manner. Fig. 22 As shown, AP1 may transmit a second repetitive beacon (indicated by 2205) only after B4 window 2204. That is, the duration between two consecutive windows allocated to AP1 (eg, TBTT) may be greater than the length of the windows allocated to AP2, AP3, and AP4.

[0191] In another embodiment, there may be a time gap between two adjacent windows. For example, there may be a duration ( Fig. 22 (not shown in FIG. 1 ). The remaining windows may be designed in a similar manner. In this case, AP1 may transmit the second repeated beacon only after the B4 window. That is, the duration between two consecutive windows allocated to AP1 (e.g., TBTT) may be greater than the length of the windows allocated to the remaining APs in the group plus the time gap between each two adjacent windows.

[0192] It should be understood that Fig. 22 The above embodiments and examples shown are given by way of example only, and they are not intended to be exclusive or limiting of the present application. For example, there may be more than (or less than) 4 APs in a group, and the windows of these APs may be designed in a similar manner as discussed above, as long as those repeated beacons can be transmitted separately without overlapping each other.

[0193] Fig.23 Another example of the above window is shown in FIG. In this example, each AP is allowed to transmit repeated beacons only within the window allocated to it. Fig.23As shown, B1 represents a repeated beacon transmitted by AP1, and "No B1 Tx" represents a window allocated for AP1. AP1 may not be allowed to transmit its repeated beacon within "No B1 Tx". B2 represents a repeated beacon transmitted by AP2, and "No B2Tx" represents a window allocated for AP2. AP2 may not be allowed to transmit its repeated beacon within "No B2 Tx". B3 represents a repeated beacon transmitted by AP3, and "No B3 Tx" represents a window allocated for AP3. AP3 may not be allowed to transmit its repeated beacon within "No B3 Tx". B4 represents a repeated beacon transmitted by AP4, and "No B4 Tx" represents a window allocated for AP4. AP4 may not be allowed to transmit its repeated beacon within "No B4 Tx".

[0194] like Fig.23 As shown, repeated beacons (e.g., B1, B2, B3, and B4) may be transmitted separately without overlapping each other. At the same time, the duration of the window "No B1 Tx" may be long enough to allow the remaining APs (e.g., AP2, AP3, and AP4) to complete their repeated beacon transmissions. In addition, the duration of the window "No B2Tx" may be long enough to allow the remaining APs (e.g., AP3 and AP4) to complete their repeated beacon transmissions. In addition, the duration of the window "No B3 Tx" may be long enough to allow the remaining APs (e.g., AP4) to complete their repeated beacon transmissions.

[0195] like Fig.23 As shown, the windows may share the same length. For example, the window "No B1 Tx" may have the same length as the window "No B2 Tx". Fig.23 As shown, AP1 may transmit the second repeated beacon (indicated by 2301) only after the window "No B4 Tx". That is, the duration between two consecutive repeated beacon transmissions (e.g., TBTT) may be greater than the duration from the start point of the window "No B2Tx" to the end point of the window "No B4 Tx".

[0196] It should be understood that Fig.23 The above embodiments and examples shown are given by way of example only, and they are not intended to be exclusive or to limit the present application. For example, there may be more than (or less than) 4 APs in a group, and the windows of these APs may be designed in a similar manner as discussed above, as long as those repeated beacons can be transmitted separately without overlapping each other. For another example, Fig.23 The windows shown may not share the same length. In this case, API may transmit a second repetitive beacon only after the end point of the window "No B4 Tx".

[0197] The process at 1902 will be discussed as follows. Fig.19 As shown, at 1902, method 1900 may include decoding at least one public information part of the plurality of public information parts or a combination of one or more public information parts to obtain a first parameter. Therefore, the processor is configured to decode at least one public information part of the plurality of public information parts or a combination of one or more public information parts to obtain the first parameter.

[0198] As discussed above, in an AP group, the common information part may include the same information. Therefore, decoding a subset of the common information part may obtain the necessary information required for other processes after the process at 1902. In one embodiment, decoding only one common information part from all received common information parts may be good enough. For example, if the transceiver receives four common information parts from our APs respectively and the four common information parts are the same, the processor may decode only one common information part (any one of the four common information parts) to obtain a first parameter. In another embodiment, one or more of the received common information parts may be buffered, combined and decoded to obtain a first parameter. For example, if the transceiver receives a first common information part from AP1, a second common information part from AP2, and a third common information part from AP3, the processor may decode the combination of the first common information part and the second common information part to obtain a first parameter. The processor may also decode the combination of all the above three common information parts to obtain a first parameter. The following will further describe the method for decoding a combination of multiple common information parts with reference to the process for obtaining the total number of APs in the group.

[0199] Preferably, the process at 1902 may further include: buffering a plurality of public information parts; combining a plurality of public information parts; and decoding the combined public information parts. Therefore, in order to decode at least one public information part to obtain the first parameter, the processor may be configured to buffer a plurality of public information parts, combine a plurality of public information parts, and decode the combination of public information parts.

[0200] The first parameter may indicate the maximum number of APs that can be selected for multi-AP transmission. Generally speaking, method 1900 may return feedback indicating the desired AP combination for multi-AP transmission to the AP group, and then the AP group may use the feedback to select one or more APs for multi-AP transmission. Therefore, the maximum number of APs to be selected for multi-AP transmission may also indicate how many APs the desired AP combination may have at most. In other words, the first parameter may indicate how many APs the STA can select for calculation at most in order to obtain the desired AP combination. For example, the first parameter may indicate that the maximum number of APs that can be selected for multi-AP transmission is M. In other words, there may be at most M APs in the desired AP combination. Preferably, M is 2. That is, in a preferred embodiment, the first parameter may indicate that at most two APs in the group may be selected for multi-AP transmission. The first parameter should not exceed the total number of APs in the group. The following description will further describe the first parameter with reference to the following detailed embodiments. It should be noted that in this application, unless otherwise specified, the terms "AP combination" and "combination of APs" may be used interchangeably.

[0201] The first parameter may indicate a preferred multi-AP scheme to be used to enable the STA to perform calculations at a later process (e.g., the process at 1904). The preferred multi-AP scheme may indicate a manner of estimating a decoding metric (e.g., a second parameter described later). It should be noted that the decoding metric may also be independent of the multi-AP scheme, and the manner in which the AP group selects the AP may depend on the specific implementation. It should also be noted that the first parameter may not be the only parameter obtained from the public information portion. Other parameters may also be obtained from the public information portion as long as they can contribute to the implementation of the principles of the present application. For example, a fourth parameter (described below) may be obtained from a combination of one or more public information portions.

[0202] The process at 1903 will be discussed as follows. Fig.19 As shown, at 1903, method 1900 may include decoding the plurality of AP-specific information portions to obtain a plurality of second parameters, each second parameter being associated with one of the plurality of APs. Thus, the processor may be configured to decode the plurality of AP-specific information portions to obtain a plurality of second parameters, each second parameter being associated with one of the plurality of APs.

[0203] The STA can identify a specific AP by decoding the AP-specific information. The second parameter may be a decoding metric that can be used to indicate the ability of the AP to support multi-AP transmission with the STA. Preferably, the second parameter may include any one of the following parameters: signal-to-noise ratio (SNR), signal-to-interference-plus-noise ratio (SINR), reference signal received power (RSRP), and reference signal received quality (RSRQ). The above exemplary second parameter may be regarded as an indicator of network quality. Therefore, the STA can perform calculations based on the network quality, thereby providing a result of the desired AP combination.

[0204] Although the above description has described some examples of the second parameter, they are not intended to be exclusive or to limit the present application. The second parameter can also be any other decoding metric or parameter, as long as they can contribute to the principle of the present application. The following description will further describe the second parameter with reference to the detailed embodiment.

[0205] The process at 1904 will be discussed as follows. Fig.19 As shown, at 1904, method 1900 may include generating feedback based on the first parameter, the plurality of second parameters, and the total number of the plurality of APs. Thus, the processor may be configured to generate feedback based on the first parameter, the plurality of second parameters, and the number of the plurality of APs.

[0206] The STA can obtain the total number of APs in the group by decoding the public information portion from the AP. Fig.18As shown, a STA (or transceiver) may receive one packet or transmission (e.g., a common information portion from AP1), and then the STA may attempt to decode the packet or transmission. If the STA cannot decode the packet or transmission, and the STA may know that more repeated transmissions may follow, the STA may buffer the received packet or transmission (e.g., log likelihood ratio (LLR) or received demodulated complex number). The receiver may then continue to receive the following repeated transmissions, such as the common information portion from AP2. Once the receiver receives a signal that may be a repeated transmission for the buffered signal, the STA may combine the received signal (e.g., the common information portion from AP2) with the buffered signal (e.g., the common information portion from AP1) and then decode. If the STA cannot decode the combined signal, and the STA may know that more repeated transmissions are expected, the STA may buffer the updated signal (e.g., a combination of the common information portions from AP1 and AP2). And then, in a similar manner, the STA may receive, buffer, and combine more signals (e.g., common information portions from AP3 and AP4) until the STA successfully decodes the combined signal. In this way, the STA can know the parameters (e.g., the first parameter described above) obtained from decoding the common information part. In the same way, the processor can know the total number of APs in the group. For example, if the processor buffers, combines, and decodes four common information parts, the processor can know that the total number of APs in the group is 4. In one embodiment, the total number of repetitions may be in the PHY layer signaling and decoded before decoding the common information part. In another embodiment, the processor can obtain the number of APs in the group by decoding the received AP-specific information part. For example, if the processor decodes 4 AP-specific information parts, the processor will know that the total number of APs in the group is 4.

[0207] It should be understood that the above embodiments and examples of the number of APs are given by way of example only, and they are not intended to be exclusive or to limit the present application. The number of APs in a group can be obtained by any other available methods as long as they can help to realize the principles of the present application.

[0208] Preferably, the process at 1904 may include the following two sub-processes: performing calculation based on the first parameter, the plurality of second parameters and the number of the plurality of APs to obtain a calculation result; and generating feedback based on the calculation result.

[0209] The processor may perform calculations based on the first parameter, the obtained second parameter (i.e., decoding metrics), and the number of APs. After the calculations, one or more AP combinations may be obtained. Based on the above-mentioned first parameter, the desired AP combination may include at most M APs. Therefore, in each obtained AP combination, there may be only one AP or multiple APs (i.e., less than or equal to M APs). The calculation may be performed mainly on the decoding metrics, thereby obtaining new decoding metrics. In this application, those new decoding metrics obtained from the calculations may be referred to as third parameters. Preferably, the calculation results may include one or more AP combinations. Preferably, the calculation results may also include a third parameter for each of the multiple AP combinations. The following description will further describe the AP combination and its third parameter with reference to the detailed implementation scheme. In this method, the above-mentioned calculations may be performed on the STA side, and the STA may feed back the recommended AP combination to the AP.

[0210] In one embodiment, the processor may perform the calculation by averaging the values ​​of the second parameter of the APs in each AP combination. In this embodiment, the calculation may be performed based on the following equation (1):

[0211]

[0212] In equation (1), x n represents the second parameter value of the AP; n represents the number of APs in the AP combination; and Z represents the average value of the second parameter values ​​of the APs in the AP combination.

[0213] In another embodiment, the processor may perform the calculation by calculating the difference between the average value of the second parameter of the APs in the AP group and the total average value of the second parameter of all APs in the group. In this embodiment, the calculation may be performed based on the following equation (2):

[0214]

[0215] In equation (2), x n and x m represents a second parameter value of the AP; n represents the number of APs in the AP group; and m represents the total number of APs in the group.

[0216] The following description will describe in detail the calculations performed by STA with reference to three examples.

[0217] In the first example, the following assumptions are made: the first parameter (M) is 2, indicating that there are at most two APs in the desired AP combination; the total number of APs is 4; the second parameter is the SINR value of each AP; the SINR value of AP1 is 6, the SINR value of AP2 is 12; the SINR value of AP3 is 18; and the SINR value of AP4 is 24. It should be noted that since there are at most two APs in the desired AP combination, the desired combination may include only one AP or at most two APs. All potentially eligible AP combinations should be counted. Based on the first parameter and the number of APs, there are 4 ways to select a single AP from four APs, and there are 6 ways to select two APs from four APs (i.e., ), that is, a total of 10 different AP combinations: (1) AP1; (2) AP2; (3) AP3; (4) AP4; (5) AP1+AP2; (6) AP1+AP3; (7) AP1+AP4; (8) AP2+AP3; (9) AP2+AP4; and (10) AP3+AP4. For an AP combination including two APs, the STA can obtain the SINR value of the AP combination by averaging the two SINR values ​​of the two APs in the AP combination based on the above equation (1). For example, the SINR value of the AP combination including AP2 and AP3 is 15. Therefore, after the calculation discussed above, the STA can obtain the following Table 1. As shown in Table 1, those obtained SINR values ​​shown in the second row are the third parameters of the obtained AP combination shown in the first row.

[0218]

[0219] Table 1

[0220] As shown in Table 1, the calculation result includes a plurality of AP combinations and a plurality of SINR values ​​(ie, the third parameter) shown in the first row, each of which corresponds to an AP combination.

[0221] In the second example, there are the same assumptions as those in the first example described above. That is, the first parameter is 2, indicating that there are at most two APs in the desired AP combination; the number of APs is 4; the second parameter is the SINR value of each AP; the SINR value of AP1 is 6, the SINR value of AP2 is 12; the SINR value of AP3 is 18; and the SINR value of AP4 is 24. The difference between the second example and the first example is the way in which the calculation is performed. In the second example, the STA may perform the calculation based on the above equation (2). After the calculation, the STA may obtain the following AP combination with the SINR values ​​shown in Table 2.

[0222]

[0223] Table 2

[0224] In the third example, there are the following assumptions: the first parameter is 3, indicating that there are at most three APs in the desired AP combination; and the other assumptions are the same as those in the first example above. The STA can perform calculations based on the above equation (1). After the calculation, the STA can obtain the following AP combination with the SINR values ​​shown in Table 3.

[0225]

[0226] Table 3

[0227] AP Portfolio AP1+AP2+AP3 AP1+AP2+AP4 AP1+AP3+AP4 AP2+AP3+AP4 SINR value (dB) 12 14 16 18

[0228] Table 3 (continued)

[0229] It should be noted that although the above description describes some examples of calculations and two equations that can be used for calculations, they are not intended to be exclusive or to limit the present application. The calculations can be performed based on any other available equations, as long as these equations can help implement the principles of the present application. For example, STA can perform calculations based on variance equations, standard deviation equations, etc. It should also be noted that the above examples and those parameter values ​​are given by way of example, and they are not intended to limit the present application.

[0230] The following embodiments will describe how to generate feedback based on the calculation results.

[0231] In one embodiment, the feedback may include at least one of the plurality of AP combinations based on the calculation results obtained from the process at 1904. In other words, the STA may not transmit all of the calculation results including all AP combinations obtained from the calculation, but may transmit only a portion of the AP combinations.

[0232] For example, when decoding the common information portion, the processor may obtain a fourth parameter (K), which indicates that the STA may feed back the best K AP combinations to the AP group. In the above first example with Table 1, if K=6, the feedback may include the following AP combinations: AP4 (SINR value=24); AP3+AP4 (SINR value=21); AP2+AP4 (SINR value=18); AP3 (SINR value=18); AP2+AP3 (SINR value=15); and AP1+AP4 (SINR value=15). In this example, the AP receiving the feedback may select a specific AP combination from the above 6 AP combinations for multi-AP transmission. It should be noted that the above examples of K are given by way of example only and are not intended to limit the present application. In one embodiment, the fourth parameter may be obtained by decoding the common information portion. The method for obtaining the fourth parameter may be similar to the method for obtaining the above first parameter. For example, if the transceiver receives a first common information part from AP1, a second common information part from AP2, and a third common information part from AP3, the processor may decode the combination of the first common information part and the second common information part to obtain a fourth parameter. The processor may also decode the combination of all three common information parts to obtain a fourth parameter.

[0233] In one embodiment, the feedback may include the calculation results obtained from the process at 1904. That is, at process 1905, the STA may transmit all of the obtained calculation results to the APs in the group. As discussed above, the calculation results may include one or more AP combinations and a new decoding metric (i.e., a third parameter) for each AP combination. In this embodiment, the AP in the group receiving the feedback may select a specific AP combination from all of the multiple AP combinations obtained from the calculation (e.g., the AP combinations shown in Table 1) for multi-AP transmission.

[0234] Preferably, the feedback may include at least one of the plurality of AP combinations obtained from the calculation and a third parameter associated with each of at least one of the plurality of AP combinations. In the above first example with Table 1, the feedback may be shown as the following Table 4 (assuming K=6):

[0235] AP Portfolio AP3 AP4 AP1+AP4 AP2+AP3 AP2+AP4 AP3+AP4 SINR value (dB) 18 24 15 15 18 21

[0236] Table 4

[0237] The purpose of transmitting the obtained SINR value (ie, the third parameter) to the APs in the group is to let the AP group know the third parameter for each obtained AP combination. Then, the AP group can select the desired AP combination for multi-AP transmission based on the third parameter.

[0238] In one embodiment, the feedback may include an AP bitmap based on the calculation results. The bitmap may be considered a piercing AP bitmap. In the piercing AP bitmap, APs that are not selected in the AP combination will not be shown, or such APs will be indicated as unavailable. In this case, such APs may be considered to be pierced from the bitmap. The bitmap size may be the same as the number of APs in the group or the number of beacons in the repeated beacon transmission. In the above third example with Table 3, if the STA wants to transmit feedback including the AP combination AP2+AP3+AP4, the AP bitmap may be shown in the following Table 5:

[0239] 0 1 1 1

[0240] Table 5

[0241] As shown in Table 5, each number represents an AP, and there are four APs (AP1-AP4 from the left end to the right end); "0" indicates that AP1 is not in the AP combination. "1" indicates that AP2-AP4 are in the AP combination. It should be understood that the bitmap included in the feedback may vary based on the APs in the AP combination, and the above example of the bitmap shown in Table 5 is given by way of example only and is not intended to limit the present application.

[0242] In one embodiment, the feedback may include multiple fields, and each of the multiple fields may include a third parameter and an AP identifier that identifies the AP combination. In other words, the STA may transmit feedback including multiple fields, each of which may combine an AP (or AP set) identifier and a corresponding third parameter (e.g., a calculated SINR value). In the above first example with Table 1, a 4-bit field AP identifier may be defined so that each bit may correspond to a specific AP in the group. For example, "1010" may indicate that AP1 and AP3 are selected in the AP combination. In the above first example with Table 1, the feedback transmitted by the STA may be shown as in Table 6 below (assuming K=6).

[0243] Identifier 0010 0001 1001 0110 0101 0011 SINR value (dB) 18 24 15 15 18 21

[0244] Table 6

[0245] As shown in Table 6, the field consists of a pair of AP identifiers and SINR values. There are 6 fields in total, each of which represents an AP combination obtained from the calculation. It should be noted that the above Table 6 and its 4-bit field AP identifier indicating the AP in each AP combination are given only by way of example, and are not intended to limit the present application. Any other available identifiers may be used to indicate an AP combination, as long as they can help to implement the above principles of the present application.

[0246] Preferably, the feedback can be sorted in multiple ways. That is, the AP combinations in the calculation results can be sorted in multiple ways. For example, the AP combinations can be in descending order based on the SINR value. In the above first example shown in Table 1, the feedback transmitted by the STA can be shown as the following Table 7 (assuming K=6):

[0247] AP Portfolio AP4 AP3 AP2+AP4 AP1+AP4 AP2+AP3 AP3+AP4 SINR value (dB) 24 18 18 15 15 21

[0248] Table 7

[0249] As shown in Table 7, the six AP combinations are listed in descending order based on their SINR values. The order of the AP combinations may implicitly identify the APs selected by the AP group. That is, the AP group may select an AP based on the order of the AP combinations transmitted in the feedback.

[0250] It should be noted that Table 7 above and the exemplary descending order are given by way of example only, and are not intended to be exclusive or limiting of the present application. The AP combinations in the feedback may be listed in ascending order based on the SINR value. In another embodiment, the AP combinations in the feedback may be listed based on the number of APs in each AP combination. For example, those AP combinations that include two APs may be listed before those AP combinations that include only one AP. It should be noted that the order of the AP combinations may not be limited to the bitmap order as discussed above.

[0251] In one embodiment, if the AP combination is unqualified, the calculation result may indicate that the AP combination is invalid. For example, in the above second example shown in Table 2, those AP combinations whose SINR values ​​are lower than "0" may be considered unqualified, and thus, the AP combination whose SINR value is lower than "0" may be indicated as "invalid". In this case, in the above second example, the STA may obtain the following AP combination with the SINR value shown in Table 8.

[0252]

[0253] Table 8

[0254] The process at 1905 will be discussed as follows. Fig.19 As shown, at 1905, the method may include transmitting feedback to at least one of the plurality of APs. The AP receiving the feedback may select an AP or multiple APs from the group for multi-AP transmission.

[0255] In some embodiments, a STA may be able to connect to a single AP. In some such embodiments, a STA may be polled by a master AP (i.e., the AP associated with the STA). A STA may be triggered by the master AP for UL OFDMA / UL MU-MIMO or UORA. The master AP may send an NDP feedback trigger to the STA, and any STA with feedback to send may indicate that it has feedback to send. The master AP may then trigger or poll the STA. Fig.24 STA1 and STA2 shown in FIG. 1 can transmit feedback based on the above scheme. Fig.24 As shown, AP1 may transmit feedback (FB) poll 2401 to STAs (STA1-STA4), and then the result indicates that only STA1 has feedback (FB) 2404 to transmit. Therefore, STA1 may transmit FB 2404. Similarly, STA2 and STA3 may transmit FB poll 2402 and FB poll 2403, respectively, and the result indicates that only STA2 has FB 2405 to transmit. It should be noted that Fig.24 The above-described embodiments shown with respect to FB pools and FB transmissions are given by way of example only, and are not intended to be exclusive or limiting of the present application.

[0256] In some embodiments, a STA cannot connect to a single STA. A set of APs may send a feedback poll or NDP feedback trigger to a STA. Any STA that cannot listen to a single AP but can listen to the poll or trigger may transmit feedback to the AP. Fig.24 STA3 and STA4 shown in FIG. 1 can transmit feedback based on the above scheme. Fig.24 As shown, AP1 and AP2 can be regarded as a set of APs that transmit feedback pools or NDP feedback triggers. Both of them can transmit the same FB pool (2406, 2406') to the STA, and the result shows that the STA has no feedback to transmit. AP1 and AP3 can be regarded as a set of APs that transmit feedback pools or NDP feedback triggers. Both of them can transmit the same FB pool (2407, 2407') to the STA, and the result shows that STA3 has FB 2408 to transmit. AP2 and AP3 can be regarded as a set of APs that transmit feedback pools or NDP feedback triggers. Both of them can transmit the same FB pool (2409, 2409') to the STA, and the result shows that STA4 has FB 2410 to transmit.

[0257] The AP may set up its multi-AP transmission based on feedback. In some embodiments, the multi-AP announcement frame may include the AP and STA selected for a specific multi-AP transmission. In some embodiments, the above feedback and calculation results (e.g., the fields discussed above, AP identifiers, bitmaps) may be exchanged between the AP and the STA using a control frame, a management frame, a PLCP header of any frame, or a MAC header of any frame. After selecting an AP based on feedback transmitted from a STA at process 1905, the selected AP may perform multi-AP transmission to the STA (e.g., multi-AP data transmission).

[0258] In another embodiment, at 1904, the STA may transmit the first parameter, the plurality of second parameters, and the number of the plurality of APs to at least one AP in the group. Then, the above calculation may be performed on the AP side. That is, the feedback generated by the processor at 1904 may include the first parameter, the plurality of second parameters, and the number of the plurality of APs. For example, the STA may obtain a first parameter indicating a maximum of two APs in the desired AP combination; the total number of APs, i.e., 4; the second parameter is the SINR value of each AP; the SINR value of AP1 is 6, the SINR value of AP2 is 12; the SINR value of AP3 is 18; and the SINR value of AP4 is 24. Then, the AP receiving the feedback may perform the above calculation and obtain the desired AP combination including one or more APs based on the calculation. In one method, the STA may directly feed back the quantized SINR value to the AP. In one method, the STA may calculate the average SINR value as SINR_average. Then, the difference between SINR_average and the SINR value is calculated as SINR_diff_k=SINR_average-SINR_k. Here k is the AP index. The STA may feed back the quantized SINR_diff_k value.

[0259] Then, the method 1900 may include: at 1906, receiving a multi-AP transmission from a combination of one or more APs. Therefore, the transceiver may be further configured to receive a multi-AP transmission from a combination of one or more APs. Since the first parameter M indicates the maximum number of selected APs (i.e., there are at most M APs in the desired AP combination), the multi-AP transmission may be performed by multiple APs in the group, i.e., the number of APs selected for the multi-AP transmission (i.e., the number of APs in the selected AP combination) should be less than or equal to M. Preferably, the multi-AP transmission may be performed by a combination of two or more APs.

[0260] Although features and elements are described above in specific combinations, it will be understood by those of ordinary skill in the art that each feature or element may be used alone or in any combination with other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted via a wired or wireless connection) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media (such as built-in hard disks and removable disks), magneto-optical media, and optical media (such as CD-ROM disks and digital versatile disks (DVDs)). A processor associated with software may be used to implement a radio frequency transceiver for a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

1. A method for multi-access point (AP) transmission, the method comprising: receiving a plurality of repeated beacons, one repeated beacon from each of a plurality of APs, each of the plurality of repeated beacons comprising a common information portion and an AP-specific information portion; decoding at least one public information part of the plurality of public information parts to obtain a first parameter; decoding the plurality of AP-specific information portions to obtain a plurality of second parameters, each second parameter being associated with one of the plurality of APs; generating feedback based on the first parameter and the plurality of second parameters and a number of the plurality of APs; as well as The feedback is transmitted to at least one of the plurality of APs.

2. The method of claim 1 , wherein the generating feedback based on the first parameter and the plurality of second parameters and the number of the plurality of APs comprises: performing calculation based on the first parameter, the plurality of second parameters, and the number of the plurality of APs to obtain a calculation result; as well as The feedback is generated based on the calculation result.

3. The method according to claim 1, further comprising: A multi-AP data transmission is received from the plurality of APs based on the feedback.

4. The method according to claim 1, wherein the decoding of at least one public information part to obtain the first parameter comprises: buffering the plurality of common information portions; combining the plurality of common information portions; as well as The plurality of common information portions are decoded. The method according to claim 1 , wherein the number of the plurality of APs is obtained by decoding the plurality of AP specific information parts.

6. The method of claim 1, wherein in each repeated beacon, the common information part and the AP specific information part are aggregated together without an inter-frame spacing therebetween.

7. The method of claim 1, wherein in each repeated beacon, the common information portion and the AP specific information portion are transmitted with an interframe space therebetween.

8. The method of claim 1, wherein the second parameter is a signal-to-noise ratio (SNR) or a signal-to-interference-plus-noise ratio (SINR).

9. The method according to claim 2, wherein the calculation result includes a plurality of AP combinations.

10. The method of claim 1, wherein the feedback comprises a plurality of fields, each of the plurality of fields comprising a third parameter and an identifier identifying a combination of two or more APs.

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